Concentration of ores



purity in the treatment of certain tin ores.

Patented Aug. 7, 1945 OFFICE CONCENTRATION OF ORES Antoine M. Gaudin, Newtonville, Mass.

No Drawing. Application January 26, 1944, Serial No. 519,818

9 Claims. (Cl. 209-466) This invention relates to a process for treating materials containing tin-bearing mineral to produce a tin concentrate and especially material containing cassiterite and siderite.

Iron carbonate, or siderite, is a troublesome im- Because of its relatively high specific gravity, siderite is not easily separated from cassiterite by gravity methods. Accordingly, the capacity of gravity concentrating equipment is much reduced and the grade of the tin concentrate is lowered. If an attempt is made to produce a high-grade tin concentrate by such method, the total recovcry of tin suffers. Until now there has been no method for separating cassiterite from siderite other than gravity methods with the limitations set forth above.

The principal object of the invention accordingly is to produce a simple, efficient process for producing tin concentrates from tin-bearing materials especially those containing cassiterite and siderite.

The invention comprises the novel processes and step of processes, the specific embodiments of which are described hereinafter by way of example and in accordance with which I now prefer to practice the invention. It also includes agents employed in such processes.

I have found in accordance with my invention that it is possible to separate cassiterite from siderite or mixtures containing same by flotation, the flotation operation being applied either to a low grade concentrate made by gravity, or to the raw ore itself, or to the ore itself after removal therefrom of certain minerals (e. g., of the sulfide minerals by a prior flotation operation). In my process the pulp is aerated, whereby the siderite becomes air-adherent, while the cassiterite does not. The siderite along with foliated siliceous mineral and residual sulfides are removed from the cassiterite-enriched pulp. Other useful separations are also obtained, for instance of foliated siliceous mineral from quartz, of siderite from fluorite and of siderite from quartz. In the claims, where the word ore" is used, it is intended to cover the minerals mentioned, including the raw ore, ore from which sulfides have been removed, and concentrates of various sorts. The

term siliceous foliated mineral is intended to designate micas, chlorites, and similar foliated siliceous materials.

To carry out this operation in accordance with my invention, the reagent combination must include an amine which contains a long hydrocarbon chain, for instance but without limitation a primary aliphatic amine having a hydrocarbon chain of at least 12 carbon atoms. I have employed satisfactorily for this purpose include oleyl amine, palmityl amine, lauryl amine, stearyl amine. I may employ a single amine for this purpose or a mixture of two or more amines.

Amines which The amine reagent can be added as such, or in the form of a solution or suspension. In many cases it is mechanically convenient to add it in the form of one of its salts, such as the hydrochloride or the acetate. That is, many amine salts are much more soluble in water than the amines themselves and, therefore, easier to prepare in the form of dilute dispersions or solutions.

To avoid flotation and loss of cassiterite with the siderite, it is necessary to carry out the opera tion in a strongly alkaline pulp, preferably at a pH between about 11 and about 12.5. If the pH is too low, cassiterate may be floated with siderite. If the pH is too high, the quantity of amine required to float the siderite becomes large.

When amines are used as flotation agents in alkaline pulps as in my process, the solubilities of the amines are quite small. If the amines are added to strongly alkaline pulps in the form of their soluble salts (e. g., hydrochlorides or acetates), the soluble salts may give the relatively insoluble amines. Thus, as in other well known floation processes using slightly soluble or insoluble reagents, a short period of conditioning or agitation to thoroughly mix or disperse the amine in the pulp may be helpful,

In some instances, substances providing certain ions, other than or in addition to hydroxyl and alkali-metal ions, are helpful as inorganic modifying agents in carrying out my process. Among such ions are the following: cyanide, metasilicate, metaphosphate, hexametaphosphate, arsenate; carbonate, phosphate and silicate. These ions should be in the form of compounds which are soluble in the aqueous pulp solution. Alkalimetal salts, such as sodium cyanide, sodium metasilicate, sodium metaphosphate, sodium hexametaphosphate, sodium arsenate, sodium carbonate, sodium phosphate and sodium silicate and such salts where the sodium is replaced by potassium are given as examples but without limitation.

Though the amines themselves may cause suificient nothing for flotation, in some instances the addition of a separate frothing agent gives improved results. For example, I have used in my process, pine oil, cresylic acid, terpineol and du Pont alcohol frother, 3-23. These frothing agents appear to act to some extent as dispersing or emulsifying agents for the amines, thereby improving the operation.

In some instances the results are improved by the addition of insoluble hydrocarbon oils, fuel oils, kerosene, gas oils, turpentine, and the like with or without frothing agents.

The following are specific examples of the manner in which I now prefer to carry out my invention. It is to be understood that these examples are illustrative and that the invention is not to be considered as restricted thereto except as inchcated in the appended claims.

Examples 1. Five hundred grams of a low-grade gravity concentrat from the Colquiri Mines in Bolivia, having the following approximate analysis:

Per cent Cassiterite About 30 Siderlte About 50 Fluorite out 15 Miscellaneous minor minerals ..About 5 were ground in a pebbl mill for 15 minutes with enough water to produce a freely flowing mud.

' The ore assayed 24.04% tin. This mud or pulp was transferred to a Fagergren flotation machine to which the following reagents were added:

Lbs. per ton Pine oil 04 Amine No. 12-NAM-118L2C Sodium hexametaphosphate Sodium hydroxide 16.0

weighed 289.3 grams and assayed 4.85% tin,

while the tailing weighed 209.5 grams and assayed 50.5% tin; 88.3% of the tin was thus collected in the non-float which can be regarded as a fairly high-grade concentrate. The float was retreated without reagent addition. After two such retreatments, the flnal float contained but 0.83% tin and weighed 210.6 grams, or 42.3% of the total weight taken. The nonfloat from such a reflotation was added to the primary nonfloat to give a tin content in the total concentrate of 41.3%; this total concentrate contained 98.5% of the tin in the material originally taken.

2. The same quantity and kind of ore was .treated as in Example 1, except that the reagents employed were:

Sodium hydroxide 16.0

The pH was 11.6. The rougher flotation tailin contained 41.6% of the total weight and assayed 51.6% tin, a cleaner tailing weighed 7.3% of the original weight and assayed 24.3% tin, while the waste product (the froth) weighed 51.1% of the original weight and assayed 1.78% tin. In this case nearly 89 per cent of the tin was gathered in a product assaying over double the assay of the feed.

If foliated siliceous minerals are present. they are floated by the amine. Because of its flaky character, a very small percentage of flne mica may promote the formation of a bulky froth. Not only is such a froth difficult to handle, but also it may cause the mechanical overflow of much material that would normally not float. Accordingly, when much mica is present, it is rireferable to deslime prior to flotation}. Although this represents a loss of part of the valuable tin in the slime, the loss is usually small and fully compensated by the saving and improved operation that results from the desliming. In the treatment of the ore from the Colquiri Mine, for example, the raw ore, or the ore after a preliminary sulfide float (using the usual anionic sultide-floating agents), contains so much foliated siliceous minerals as to make a desliming operation desirable prior to the amine float of the siderite. The following example is typical of the results that can be obtained.

'3. Seven hundred and fifty grams of the raw Colquiri ore, analyzing approximately as follows:

Per cent Sulfide minerals, including sulfldes of iron, zinc and lead About 45 Siderite ut 20 Quart; Ahnnt 1o Fluorite About 5 Cassiterite -About 5 Foliated siliceous minerals About 15 were treated for the sulfide-floating step with the following reagents:

Lbs. per ton Copper sulfate 1.5 Potassium amyl xanthate 0.5 Pine oil 0.10

The addition of these reagents produced a sulflde froth which was then cleaned by repetition of the floating operation without additional reagents, the cleaner froth weighing 42.2% of the original weight and containing 0.48% tin; that is, 6.2% of all the tin in the ore. The rougher tailing and the cleaner tailing combined were deslimed in two steps. In the flrst step,

Lbs. per ton Sodium hydroxide 3.0 Sodium hexametaphosphate 2.0

were used to disperse the ore, and in the second step,

Lbs. per ton Sodium hydroxide 2.0 Sodium hexametaphosphate 0.5

normal octadecenyi amine) 1.2 Pine nil 0.3

The pH at this stage was 11.1. The rougher siderite froth was cleaned, using Lbs. per ton Sodium hydroxide 0.6 Pine oil 0.05

The pH was 11.2. The cleaner froth weighed 27.4% of the original weight, assayed 0.62% tin. and contained 5.2% of the total tin in the sample. This froth consisted essentially of siderite, micas and chlorites, and was largely devoid of quartz. The cleaner tailing weighed 4.2% of the original weight, assayed 4.96% tin, and contained 6.4% of the total tin. The non-float, which is in effect the tin product, weighed 16.6% of the original weight, assayed 15.7% tin, and contained 80.0% of all the tin in the sample. This tin product consated essentially of cassiterite, fluorite and qua 4. The same quantity and kind of ore was treated as in Example 3. Using the same reagents in the sulfide-floating step, a cleaner froth was obtained weighing 42.8% of the original weight and containing 0.57% tin; that is, 7.6% of all the tin in the ore. The rougher tailing and the cleaner tailing combined were deslimed in two steps. In the first step, sodium metasilicate in the amount of lb. per ton of ore was used to disperse the ore, and in the second step no reagents were used. The slirne weighed 9.5% of the total weight, assayed 0.83% tin, and contained only 2.5% of the total tin. The siderite (together with non-slimed mica) was floated after addition of the following reagents:

The pH in the roughing stage was 11.3. The

rougher siderite froth was cleaned, using Lbs. per ton Sodium hydr xi 0.8 Pine nil 0.2

The cleaner froth weighed 29.9% of the original weight, assayed 0.77% tin, and contained 7.2% of the total tin in the original sample of ore. The cleaner tailing weighed 6.9% of the original weight, assayed 6.17% tin, and contained 13.3% of the total tin. The nonfloat, which is in effect the tin product, weighed 10.9% of the original weight, assayed 20.4% tin, and contained 69.4% of all the tin in the sample.

It is well known that amines may be used to float sulfides. I have found that the minor quantities of sulfide minerals that occur with the siderite and the cassiterite are floated with the siderite under the siderite-floating conditions described in this disclosure. In fact, the sulfldes are floated even upon addition of the most minute quantity of amine, and ahead of either siderite or foliated siliceous minerals. For example, the very small quantities of several sulflde minerals still present in the low grade Coiquiri gravity concentrate (a gravity concentrate from which the bulk of the sulfides has already been removed by anionic-collector flotation of the sulfide) are readily removed with the siderite, thus producing a tin concentrate in the nonfloat that is substantially sulfur-free. This is advantageous, since penalties are provided in tin smelting for sulfur and for such metals as lead, antimony, and bismuth.

In the above examples, suitable proportions of the other inorganic modifying agents men- .tioned above, namely, sodium or potassium cyanides, metasilicates, metaphosphates, hexametaphosphates, arsenate, carbonate, phosphate, and silicate may be substituted for those used in the examples.

Other amines such as oleyl amine, palmityl amine, lauryl amine, and stearyl amine, either alone or in combination, may be substituted for the amines in the above examples.

What I claim is:

chain having at least 12 carbon atoms at a pH of about 11 to about 12.5, aerating, and remov- 1. A process for treating ores containing cas- I siterite and siderite which comprises, treating the pulped ore with a reagent containing an amine having a non-aromatic hydrocarbon ing siderite adhering to air from the cassiteriteenriched pulp.

2. A process for treating ores containing cassiterite, foliated siliceous mineral and siderite siderite and fluorite which comprises treating th pulped are with a reagent containing an amine having a non-aromatic hydrocarbon chain having at least 12 carbon atoms at a pH of about 11 to about 12.5, aerating and removing the siderite adhering to air from the fluorite-enriched pulp.

4. A process for treating ores containing siderite and quartz which comprises treating the pulped ore with a reagent containing an amine having a non-aromatic hydrocarbon chain having at least 12 carbon atoms at a pH of about 11 to about 12.5, aerating and removing siderite adhering to air from the quartz-enriched pulp.

5. A process for treating ores containing cassiterite and siderite which comprises, treating the pulped ore with a reagent containing an aliphatic amine having at least 12 carbon atoms in the hydrocarbon chain at a pH of about 11 to about 12.5, aerating and removing siderite adhering to air from the cassiterite-enriched pulp.

6. A process for treating ores containing cassiterite and siderite which comprises, treating the ulped ore with a reagent containing a frothing agent, a dispersing agent, a causticalkali, and an amine having a non-aromatic hydrocarbon chain having at least 12 carbon atoms at a pH of about 11 to about 12.5, aerating and removing siderite adhering to air from cassiteriteenriched pulp.

7. A process for treating ores containing cassiterite and siderite which comprises, treating the pulped ore with a frothing agent, sodium hexametaphosphate, sodium hydroxide, and a mixture of amines containing an octadecyl amine, a hexadecyl amine and an octadecenyl amine at. a pH of about 11 to about 12.5, aerating, and removing siderite adhering to air from the cas-.

siterite-enriched pulp.

8. A process for treating ores containing cassiterite, foliated siliceous mineral and siderite which comprises, dispersing and desliming the pulped ore with a dispersing agent, treating the deslimed ore with a reagent containing a primary aliphatic amine having at least 12 carbon atoms in a hydrocarbon chain at a pH of about 11 to about 12.5, aerating, and removing siderite adhering to air from the cassiterite-enriched pulp.

9. A process for treating ores containing cassiterite, mica and siderit which comprises, dispersing and desliming the pulped ore, treating the deslimed ore with a reagent containing caustic alkali, an inorganic dispersing agent, and a mixture of amines, each of said amines having a hydrocarbon chain of at least 12 carbon atoms, at a pH of about 11 to about 12.5, aerating and removing siderite adhering to air from the cassiterite-enriched pulp.

ANTOINE M. GAUDIN. 

